California-based Iron Butterfly, the band behind the 1960s psychedelic rock anthem, “In-A-Gadda-Da-Vida” — a title derived from the lead singer’s drunken slurring of the lyric “In the Garden of Eden” — charge they’re not getting properly paid for the ubiquitous classic.

Ronald Bushy, Doug Ingle, Lee Dorman and their longtime lawyer, William Coben, who has copyrights to the 17-minute-plus tune, say in a lawsuit that its continuing popularity has made them suspicious about whether their record companies are keeping track of what they should pay.

“It’s used in a lot of commercials, and a lot of movies, and a lot of TV episodes,” Bushy, the drummer, told The Post. “The last one I saw caught me by surprise. I’m a real fan of ‘Criminal Minds,’ and all of a sudden ‘Vida’ is playing — it just blew my mind.”

“We should be paid what is due. It’s only fair.”

Bushy, who turned 69 on Thursday, had a job at a pizza joint, and kept the band afloat as they played clubs like LA’s famed Whisky A Go Go.

The group recorded the classic by accident at Long Island’s Ultra Sonic recording studio. A technician asked the band to play something so he could check sound levels, and he recorded them as they played the then-unfinished “Vida” for nearly 20 minutes.

The band, which still tours, believes it’s owed at least $119,000 in back royalties since 2002, according to the Dec. 14 lawsuit against Atlantic Recording, Elektra Entertainment and Warner/Chappell Music filed in Manhattan Supreme Court. It also seeks a full accounting of royalties due from foreign sales.